Render inband text tracks in the media pipeline

content/renderer/media/texttrack_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/texttrack_impl.h"
 
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop_proxy.h"
 #include "content/renderer/media/webinbandtexttrack_impl.h"
 #include "third_party/WebKit/public/web/WebInbandTextTrackClient.h"
 #include "third_party/WebKit/public/web/WebMediaPlayerClient.h"
 
 namespace content {
 
-TextTrackImpl::TextTrackImpl(WebKit::WebMediaPlayerClient* client,
-                             WebInbandTextTrackImpl* text_track)
-    : client_(client), text_track_(text_track) {
+TextTrackImpl::TextTrackImpl(
+    const scoped_refptr<base::MessageLoopProxy>& message_loop,
+    WebKit::WebMediaPlayerClient* client,
+    scoped_ptr<WebInbandTextTrackImpl> text_track)
+    : message_loop_(message_loop),
+      client_(client),
+      text_track_(text_track.Pass()) {
   client_->addTextTrack(text_track_.get());
 }
 
 TextTrackImpl::~TextTrackImpl() {
-  if (text_track_->client())
-    client_->removeTextTrack(text_track_.get());
+  message_loop_->PostTask(
+      FROM_HERE,
+      base::Bind(&TextTrackImpl::OnRemoveTrack,
+                 client_,
+                 base::Passed(&text_track_)));
 }
 
 void TextTrackImpl::addWebVTTCue(const base::TimeDelta& start,
                                  const base::TimeDelta& end,
                                  const std::string& id,
                                  const std::string& content,
                                  const std::string& settings) {
-  if (WebKit::WebInbandTextTrackClient* client = text_track_->client())
+  message_loop_->PostTask(
+    FROM_HERE,
+    base::Bind(&TextTrackImpl::OnAddCue,
+                text_track_.get(),
+                start, end,
+                id, content, settings));
+}
+
+void TextTrackImpl::OnAddCue(WebInbandTextTrackImpl* text_track,
+                             const base::TimeDelta& start,
+                             const base::TimeDelta& end,
+                             const std::string& id,
+                             const std::string& content,
+                             const std::string& settings) {
+  if (WebKit::WebInbandTextTrackClient* client = text_track->client()) {
     client->addWebVTTCue(start.InSecondsF(),
                          end.InSecondsF(),
                          WebKit::WebString::fromUTF8(id),
                          WebKit::WebString::fromUTF8(content),
                          WebKit::WebString::fromUTF8(settings));
+  }
+}
+
+void TextTrackImpl::OnRemoveTrack(
+    WebKit::WebMediaPlayerClient* client,
+    scoped_ptr<WebInbandTextTrackImpl> text_track) {
+  if (text_track->client())
+    client->removeTextTrack(text_track.get());
 }
 
 }  // namespace content